Backlighting is commonly used in rubber keypads, membrane switches, liquid crystal displays, rigid panels, and the like, to make them more discernible and enhance their visibility. Existing techniques have utilized fiber optics for this purpose.
Typically, such prior backlighting devices utilize a light source, the light from which is transmitted via a fiber optic cable to a keyboard, or like device, for which backlighting is desired. At each of a desired number of locations on the portion of the cable positioned behind the panel to be backlit, a suitable notch is formed, typically by using a hot stamping machine. The stamping machine forms the notch by pressing against the fiber optic cable at the desired location. As the light passes down the fiber optic cable, a portion of the light will exit through the notch and illuminate the location above that region. Typically, the remaining light continues its travel along the fiber optic cable and terminates at a location remote from the notch.
In such prior devices, the light which exits through the notch provides backlighting of relatively low intensity. Also, the intensity of light along the fiber optic cable diminishes as light is reflected through a series of such notches along the fiber optic cable. Thus, although such prior devices are known to serve their purpose, they have not proven to be entirely satisfactory.
A need thus exists for an improved apparatus for providing backlighting in a device which ensures increased brightness at specific points and a uniform distribution of light for all regions of the device to be backlit.